Usability evaluation of systems for mobile computers and devices is an emerging area of research. This paper presents and evaluates six techniques for evaluating the usability of mobile computer systems in laboratory settings. The purpose of these techniques is to facilitate systematic data collection in a controlled environment and support the identification of usability problems that are experienced in mobile use. The proposed techniques involve various aspects of physical motion combined with either needs for navigation in physical space or division of attention. The six techniques are evaluated through two usability experiments where walking in a pedestrian street was used as a reference. Each of the proposed techniques had some similarities to testing in the pedestrian street, but none of them turned out to be completely comparable to that form of field-evaluation. Seating the test subjects at a table supported identification of significantly more usability problems than any of the other proposed techniques. However a large number of the additional problems identified using this technique were categorized as cosmetic. When increasing the amount of physical activity, the test subjects also experienced a significantly increased subjective workload.